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GCN Circular 17352

Subject
GRB 150126A: MAXI/GSC afterglow candidate detection
Date
2015-01-27T01:54:30Z (9 years ago)
From
Motoko Suzuki at RIKEN <motoko@crab.riken.jp>
T. Takagi (RIKEN), S. Nakahira (JAXA), M. Serino (RIKEN), H. Negoro (Nihon U.),
S. Ueno, H. Tomida, M. Kimura, M. Ishikawa, Y. E. Nakagawa (JAXA),
T. Mihara, M. Sugizaki, M. Morii, J. Sugimoto, A. Yoshikawa, M. Matsuoka (RIKEN),
N. Kawai, T. Yoshii, Y. Tachibana (Tokyo Tech),
A. Yoshida, T. Sakamoto, Y. Kawakubo, H. Ohtsuki (AGU),
H. Tsunemi, D. Uchida (Osaka U.),
M. Nakajima, K. Fukushima, T. Onodera, K. Suzuki, T. Namba, M. Fujita, F. Honda (Nihon U.),
Y. Ueda, M. Shidatsu, T. Kawamuro, T. Hori (Kyoto U.),
Y. Tsuboi, A. Kawagoe (Chuo U.),
M. Yamauchi, Y. Morooka, D. Itoh (Miyazaki U.),
K. Yamaoka (Nagoya U.)
report on behalf of the MAXI team:

The MAXI/GSC nova alert system triggered an uncatalogued X-ray transient 
source at 21:03:24 UT.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (350.503 deg, -12.368 deg) = (23 22 00, -12 22 04) (J2000)
with a statistical 90% C.L. elliptical error region
with long and short radii of 0.56 deg and 0.46 deg respectively.
The roll angle of long axis from the north direction is 145.0 deg 
counterclockwise.
There is an additional systematic uncertainty of 0.1 deg (90% containment 
radius).
The X-ray flux averaged over the scan was 55 +- 17 mCrab
(4-10keV, 1 sigma error).
There was no significant excess flux in the previous transit at UT 19:30
and in the next transit at 22:35 UT with an upper limit of 20 mCrab for 
each.

This position is about 2 degree from the position of the Fermi trigger 
#443998238. Considering the Fermi detection, the transit time, and the spectral
softness, the source is likely to be the afterglow of the GRB triggered
by Fermi.
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